There are a number of widely used processes which involve the repeated supply of a component in powder form to a processing apparatus. For example, photographic processing chemicals may be supplied in powder form to be dissolved in water before use. Such powders are often supplied in flexible material bags, especially polyethylene bags, of various sizes.
With existing mixing devices, the operator simply cuts open the bag and throws the contents into the mixer. This action results in dust which is inconvenient for the user. Dust can be reduced where the bag is of a sufficient length to hang over the upper edge of a mixer housing with its open end below the level of liquid therein. A drawback of this solution is that when a user takes the emptied bag out of the mixer, the bag is wet due to the contact with the wet chemistry in the mixer.